HATCHING TBOTJT 155 



and iineaten food is a developer of fungus. 



Dangers to the Fry. — 'With, a marked increase 

 over 15,000, there is proportionately a greater 

 amount of care and attention required and 

 greater danger of disaster. Troughs contain- 

 ing only about 15,000 will require attention about 

 once a day in addition to the three daily meals. 

 A trough containing 30,000 will require care at 

 least three or four times daily, exclusive of 

 feeding, and must be carefully scanned the first 

 thing in the morning and the last thing at 

 night. 



If trouble breaks out in a heavily stocked 

 trough the danger of a total loss is much greater 

 than where there is only a normal quantity. 

 Naturally the number must be governed some- 

 what by the temperature of the water and the 

 character of the troughs. It would be perfectly 

 safe to carry 20,000 to 25,000 for two or three 

 months after the sacs have been absorbed in 

 troughs of the Pennsylvania pattern. After a 

 couple of months there must be further thin- 

 ning. The higher the temperature the smaller 

 the number of fish that can be carried safely, 

 for the reason that with the higher tempera- 



